RE: FOC calculations...method in question
 

Id go with eastons way allso , but dont spend much time on it if any , foc is not that important , haveing great arrows that are matched to your bow , that are as close to identical is what you are looking for . One of the most critical things is to have enough stearing in the back of the arrow [ ie fletching] to counteract the stearing up front , the more stearing up front the more stearing needed in back .